You may feel and think negatively because people in your life are negative toward you or others. This negativity may make you feel bad about yourself, and in response you may act badly toward another person. It's a vicious cycle. When a friend, co-worker, family member, or even a complete stranger makes a comment that upsets you, it may set the tone for how you feel the entire day.
It shouldn't, but sometimes it does. The reasonable answer to this would be to tune out the negativity and ignore it, but it's easier said than done, right?
It can start to take a toll if you are already having trouble in your personal life, and then come across people who are spewing negativity. This is especially so, if it happens often (certain friends, or in the workplace). Negativity can be displayed in numerous ways, such as: being rude and dismissive, being passive aggressive, silent treatment, gossip etc. With this, it is easy to take this to heart and internalize what is happening. You may start to feel like you don't have control and that others are influencing your emotions.